Evaluation of a malaria rapid diagnostic test among febrile children in Sokoto, Nigeria

Abstract

Malaria rapid diagnostic test (RDT) is an antigen capture assay that enables rapid diagnosis of malaria 
without the need for electricity or highly skilled technicians. Though potentially useful, its adoption needs to 
be guided by local test sensitivity. This study evaluated the diagnostic performance of a commercially 
available RDT (Malaria Pf rapid device, Biotec Laboratories Limited, United Kingdom) among 400 febrile 
children(aged 6months to 12 years) in Sokoto, Nigeria. It was a prospective observational study conducted 
at the Paediatric Outpatient Department (POPD) of UDUTH, Sokoto between March and October, 2009. 
Finger prick blood samples were collected from each of the patients (day 0) and immediately tested for 
falciparum malaria by both Giemsa microscopy and rapid diagnostic test (RDT). Patients with both positive 
RDT and positive microscopy results on day 0 were retested on day 7 (after antimalarial therapy) by both 
diagnostic methods. The prevalence of malaria among the study cohort was 40.8% by microscopy and 
39.5% by RDT.  The RDT had a sensitivity of 90.2% and specificity of 95.4%; with positive and negative 
predictive values of 93.0% and 93.4% respectively. Test accuracy was 93.3%, whereas reliability was 85.3%. 
Test sensitivity is reduced by low parasite density (100% at > 1600/µl Vs 69.2% at <800/µl). Of the 69 patients 
who were retested on day 7 after antimalarial treatment, 18 (26.1%) still had positive RDT test even though 
negative by microscopy and afebrile at the time of follow up.  The diagnostic performance of the RDT in this 
study was good. Hence, it is recommended as an alternative method for diagnosis of malaria, especially 
when microscopy is not feasible.